MAGNETIC STORMS.

Grey River Argus, 17 March 1910, Page 4

MAGNETIC STORMS.

HOW SCIENCE EXPLAINS THEM

The recent visitation by a magnetic storm, resulting in the disorder of thfc telegraphic -operation of .'a large part of the world, is another reminder of the variableness of our so-called solid earth. It showed us that our civilisation is at the irercy of ttrrestrialforces compared with which the earthquake and the volcano r^re b\it small affairs. A Vast stream, of electric energy, taking possession of the whole bulk, of the globe, swinging the telegraph needles to the full, extent of the arc, as if the wires were occui>ied by an untamed enemy which would let •nothing thrbuglt— it all sounds like an incredible "story. It is a very old saying that we never know a -thing unless j we know' its beginnings. Not many years ago the b.-ire mention of a magnetic storm was sufficient to suggest the mysterious and unknown— it called forth so many theories and divided opinions as to its cause. In the light of more recent knowledge it is now possible to trice the origin and explain the phenomena of this wild sample of Nature's forces. The key that unlocks the mystery is not so far away, and present-day science shows us where it has been hidden. .

Everybody knows that a compass needle points north and south, the north-seeking end being attracted to the North Magnetic Pole of the earth, and the south-seeking . end to the earth' s South Magnetic Pole. These effects "arise from the fact ; that the earth itself is a gigantic magnet, and behaves very much as though it had a powerful magnet suspended within its interior. The .e.'u\th' is thus permeated by a series of lines which Faraday called ''lines of ..'magnetic force." These lines lie approximately north and 'south, and ilie needle, being itself a magnet, it coerced" to set along these, lines, and points nearly north ami ?6uth. lii some places the magnetic and the geographical north coincide; In others the needle 1 points slightly east or west of tlie geographical north, C-. ml it is always shifting! Three hundred years ago. the variation n London was to the east, now- it.. is to the- west. Moreover, th'o north -and-' "••outh line of .direction itself is not permanent. There" is a sliglit annual variation, dependent on tlte season of the year. • .Tbe.ro. is also a. daily, variation. . According .■ to.: the, t observationg of Cassini the neecJ'e is nearly at rest during the night ; at sunrise the north .^sbkiiig end moves westerly. Whatover.the di»ily yariation may be it is greatest in slimmer and. least in winter. Lastly, the position of the needle =s-.." not always truly horizontal. It dips; and the angle- of . dip varies.

- An irregular or accidental variation ftf the -needle "is called a magnetic storm. In this connection, however, the word "storm" is used in a broad sense. „ The needle thaf indicates it tells its tale very "quietly. As a rule, there is no rapid swing -..-b&ckwards arid forwards. The iieedle simply moves a little; to the east or to the west of its normal position. If it be a" telegraphic needle under the! control of the electric current it moves of its own. accord., renounces its allegiance to the current and '•.."strikes'.' by refusing; to transmit , the .ordinary vsignals'.The 1 nefedle is in-' i the power q$ a force greatly superior to 1 that which commonly sways it. Bnr- [ ing a magnetic perturbatiori there is [an electric current iji "the earth^wljjch. [ in ay- be ' a- -thousand tinies stronger ;thaii the battei / . current. Tlie direction ,| |- of. ' the eati'th current is usually from ! I east to w v -st, as though it obeyed the i'Sun. Moreover, sun spots and ;magI rietic si wnis ahnost always occur simultan >ously. .That there is an intimate. .relationship . between ' the two mauifeaTfttioiis is. now generally accepted- One of the largest sun spots •evcir • o^ueryed occurred : fiv: 1850, >md $5 appearance was accompanied for 4ev.er.al (i'ays by ;.-- a magnetic storm jjt, unpresedented ' niagnitude. During tho .receiit; '"storm" there was a - respectable iti.ii spot wEch covered about seven )«.m r b;*<T l million square mileß of solar ir; : ; ; •• Whatever may be their caiVvc^f. :"•■■■ M 3 doubt that sun spots 'ivi; "..*•' ■';. 7 :•.'•;: :v of very: violent activ- ■ ity . :;-.;■ . ,'s disc. SpotTregions in the auj and^ volcanic eriiptions. on the , earth Yire soinewliat anatagous. '' In the

forme* 1 case according to spectro scopio observations, the eruption coi> 1 sists uf. glowing hydrogen, and glowing hydrogen spoute forth a stream of electi'ified particles.

Nt.b' glowing hydrogen only, but all very hot bodies shoot out mystenocis little particles called electrons. They are shot like tiny bullets from every candle flame or burning gas ? from red hot metals, and even from metals that are impinged by ultra-violet light. This is the new doctrine which constitute one of the most interesting stories of present day science. It has been established by discoveries which can only be described as revelations, and by experiments of the most impreu siive .-and wonderful of any century. Iv the electron we have the key to some of Nature's most carefully hidden secrets. It goes under various names such a corpuscles, sub-atom, and iron It, is the smallest thing known, and, with the exception of light, probably the swiftest. The electron is a thousand times smaller than the snikU est atom known to the chemist. It flies with: a prodigious velocity, and bombards every object in its neighbourhood. Its weight and speed have been measured with a most astounding precision. Its speed depends on circumstances, but. the slowest electron flies at the rate of 10,000. and the swiftest at the rate of 90,000 miles a second. And what is this mysterious little body? ft is. a small load of clecft'icity shot offj as already said, from anything whatever that is in an incandescent state;' it may be from the sun, or from a lucifer match, or even from a plate of cold steel exposed to certain conditions

It is easy to picture our sun with its I enormous temperature emitting a contutous flood of electrons. During sun spot periods its electric attributes are largely ; augmentgd,. . . aijd 4 are flijickly felt' on, the earth as a^ppwerful electric current, which, disturbs telegraphic and other instruments. "But 'it may be asked: Why does not the sun's gravitation arrest the flight, of the corpuscles and pull them back to itself. The details of this theory do not concern us at the present moment. It may suffice to say that the pressure of light lias been measured, and it reveals a new force in the Universe. The sun's light has been found to press upon o\6 whole earth with a force of about 75,000 tons. It is s ■ force whose action is very singular* It is all push, and applies itself only to the surface of the body on which it acts. In this respect it differs from gravitation, which is all pull, and is applied to the whole body. " Light-pressure is therefore proportional to surface. If a particle be smaller than a. hundred thousandths ... part of an inch, push prevails ; being all surface, gravitation no longer holds it, and it is repelled by, the pressure behind it. The hundred-thousandth part of an inch is not very small. The electrons projected by our sun into space are much, smaller than this. The sun not only projects them, but pushes them forward, until they eventually come in contact with the upper regions of the air. Here the particles come under the magnetic influence . of the earth with its lines of force running from pole to pole. Influenced by our big planetary magnet, they are deflected towards the poles. Approaching the poles they encounter an atmosphere which is highly rarified, and there they show the discharge which takes place; when electricity passes ; through a vacuum tube^ In connection with the • recent magnetic storm it was reported that the Aurora was observed in both the North and South Polar skies. It is now maintained that^ the Aurora and the beautiful glow of the vacuum tube are the same. If the Auroroa be cruised by electrons shot from the sun and driven towards the % earth by the pressure* of light, and attracted to the poles by the earth's magnetism, then sun spots, the Aurora, and the earth's magnetism are closely related. They are actually in sympathy with each other.. With the advent of sun spots there is -also the advent of the Aurora, and the magnetic needle is affectett in -a most remarkable way. The Adelaide correspondent of the Sydney Daily Telegraph, writing on February 23rd. said :r— "At ,a big Anglican , Church in Adelaide on Sunday morning there was not a single male adult : in the congregation, and the verger had to carry round the collection plate." '